STMicroelectronics LD57100JR

Overview

LD57100JR from STMicroelectronics is an adjustable ultra-low-dropout linear regulator (LDO) with NMOS pass transistor architecture, delivering 1 A output current with 40 mV typical dropout at full load. It features dual-supply biasing (VBIAS pin), ±1% output voltage accuracy over −40 °C to +85 °C, and integrated active discharge, thermal shutdown, and current limiting. It targets low-noise post-regulation in space-constrained mobile power rails.

For engineers reviewing the LD57100JR datasheet, LD57100JR pinout, LD57100JR application, or LD57100JR equivalent, key selection criteria include its 0.5–3.0 V adjustable output range, 35 µA no-load ground current, 85 dB VBIAS PSRR (1 kHz), 27 µVRMS fixed-version output noise, and Flip Chip6 (0.8 × 1.2 mm) package compatibility with high-density PCB layouts.

Technical Context

The LD57100JR uses an NMOS pass element driven by a dedicated VBIAS supply (3.0–5.5 V), enabling ultra-low dropout even when VIN approaches VOUT - unlike PMOS-based LDOs limited by threshold voltage. Its internal reference (0.5 V ±0.5%) feeds a precision error amplifier controlling gate drive, ensuring tight regulation across load (1 mA–1 A) and temperature (−40 °C to +85 °C).

It integrates logic-controlled enable (EN), output discharge MOSFET (RON = 150 Ω), thermal shutdown (160 °C, 20 °C hysteresis), and short-circuit protection with 1.5–2.6 A current limit. The FB pin accepts resistor-divider feedback for adjustable output, while SNS pin in fixed versions enables remote sensing via dedicated PCB trace.

Key Specifications

Pinout & Package

LD57100JR is housed in a Flip Chip6 package (0.8 mm × 1.2 mm, 0.4 mm pitch), optimized for minimal footprint and thermal performance (R_thJA = 60 °C/W on standard 4-layer JEDEC board). The die is mounted face-down with solder bumps directly contacting PCB pads - no wire bonds, enabling lower inductance and improved high-frequency stability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable LDO applications.

Compared with XC6210B332MR-G and ADM7172ACPZ-R7, the LD57100JR uniquely combines 1 A current, 40 mV dropout, adjustable output, active discharge, and 0.8 × 1.2 mm footprint - making it optimal for next-gen compact, battery-sensitive, multi-rail mobile and wearable systems.

Availability

LD57100JR is available at Aetrix Electronics and suitable for smartphone application processor core rails, camera module analog supplies, wearable SoC I/O domains, and industrial IoT sensor node bias rails requiring stable component supply, long-term lifecycle support, and consistent parametric performance.

Supply support for LD57100JR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD57100JR belongs to ST's high-precision, ultra-low-dropout LDO family targeting space- and power-constrained portable electronics - engineered specifically for post-regulation of advanced SoC and sensor subsystems.

FAQ

What is the minimum required VBIAS voltage for LD57100JR at 1.2 V output?

The minimum VBIAS is the greater of 3.0 V or VOUT + 1.6 V. For VOUT = 1.2 V, VBIAS must be ≥ 2.8 V - but per specification, it must still meet the absolute floor of 3.0 V. Therefore, 3.0 V is the minimum valid VBIAS. Operating below this risks improper NMOS gate drive and increased dropout or instability.

Can LD57100JR be used without the VBIAS pin connected?

No. The VBIAS pin is mandatory and cannot be left floating or tied to GND. It powers the internal gate driver and error amplifier. If VIN satisfies both VOUT + VDROP and ≥ max(3.0 V, VOUT + 1.6 V), VBIAS may be connected directly to VIN. Otherwise, a separate clean 3.0–5.5 V bias source is required.

How does the SNS pin differ from FB in LD57100JR?

LD57100JR is the adjustable version - it uses the FB pin (not SNS) for feedback. SNS is used only in fixed-output variants (e.g., LD57100J100R) for remote voltage sensing. In LD57100JR, FB connects to the center node of the R1–R2 resistor divider to set VOUT = 0.5 V × (1 + R1/R2), with R2 ≤ 500 kΩ for accuracy.

Is external compensation required for stability with ceramic output capacitors?

No. The LD57100JR is internally compensated and stable with any good-quality ceramic capacitor ≥1.0 µF and ESR between 3–300 mΩ - including X5R/X7R types. Stability is maintained across temperature, load, and input voltage variations, eliminating need for external RC networks or compensation components.